Camouflage coverings discussed in tie prior art fail to provide an effective, passive means for suppression of the wearer's thermal (heat) signature without inducing heat stress in the wearer. The primary methods relied upon in the prior art include (1) active movement of air by means of blowers, fans, etc.; and (2) changing only the emissivity of traditionally-sewn garments so that the heat emission of the clothing is reduced.
Both of these techniques have serious drawbacks. For instance, active movement of air under a camouflage covering, produced by a blower or the like, is effective in mixing ambient air with that heated by the body, or in forcing ambient air through the fabric of the covering--thus keeping it cool by way of forced convection. However, this technique has the disadvantage of requiring the user of the covering to carry a power source to run the blower which, in addition to adding weight and reducing mobility, introduces the possibility of a failure at a time when the blower is needed for protection and/or presenting one additional heat source which can be detected by thermal sensors or the like.
The changing of the covering fabric's emissivity can reduce the apparent temperature of the wearer's clothing, but greatly reduces the amount of heat the wearer can dump to the environment--resulting in rapid heating of the wearer and heat stress. Because of this, the prior art low emissivity garments can only be worn for short periods of time, especially during heavy work. An example of a low emissivity material can be seen in the reflective suits worn by firemen and crash rescue personnel. High outside temperatures can be withstood by the wearer, but the suit can only be worn for a few minutes at a time due to the thermal heat build up of the wearer's own heat reflecting back off from the suit.
In addition, the prior art does not consider the simultaneous suppression of the near infrared signature of the wearer simultaneously with suppression of thermal and visual signatures. Near infrared suppression is important in defeating observation and detection by image intensified night viewing devices such as night vision goggles.
The prior art also suffers from the drawback of failing to provide a camouflage material that can easily be tailored to conform with the desired use such as the mission to be performed and the equipment requirements of the wearer during that particular mission. The prior art also fails to adequately maintain protection while allowing the wearer to access equipment being carried. Further, the prior art fails to provide protection from multispectral sensing in many areas of the wearer such as in the hand and face area which involves consideration of how a covering might change in position during use. The prior art also fails to adequately provide a covering which can be easily reconfigured or adjusted on the wearer such that a standard design is applicable to a wide assortment of wearer body dimensions.
U.S. Pat. No. 5,281,460 and PCT application no. PCT/US93/09114, which share a common inventor with the present application, represent an initial step in solving many of the numerous problems presented by the state of the art. The present invention, which came about following extensive testing and modifications in the infrared camouflage covering described in U.S. Pat. No. 5,281,460 and PCT application no. PCT/US93/09114, however, features some significant improvements over the covering described in the '460 patent and PCT application particularly with respect to enhancing the signature suppression effects of the covering over a wide range in the electromagnetic radiation spectrum and in making the covering better adapted for a wide variety of uses and circumstances, better able to provide protection against sensing, and more user friendly. U.S. Pat. No. 5,281,460 and PCT application no. PCT/US93/09114 are incorporated herein by reference in their entirety.